Re: [PATCH][next] io_uring: fix incorrect check for kvmalloc failure

From: Pavel Begunkov <asml.silence@gmail.com>
To: Colin King <colin.king@canonical.com>,
	Jens Axboe <axboe@kernel.dk>,
	io-uring@vger.kernel.org
Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH][next] io_uring: fix incorrect check for kvmalloc failure
Date: Mon, 26 Apr 2021 11:04:56 +0100	[thread overview]
Message-ID: <bb89db64-999e-7e39-745a-c8aaa35731bf@gmail.com> (raw)
In-Reply-To: <20210426093735.7932-1-colin.king@canonical.com>

On 4/26/21 10:37 AM, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> Currently imu is being allocated but the kvmalloc failure is checking
> imu->bvec instead of imu.  Fix this by checking imu for null.

Right, that's buggy.

fwiw, was reported by lkp and I sent a fix yesterday, so take any.
https://lore.kernel.org/io-uring/d28eb1bc4384284f69dbce35b9f70c115ff6176f.1619392565.git.asml.silence@gmail.com/T/#u

> 
> Addresses-Coverity: ("Array compared against 0")
> Fixes: 41edf1a5ec96 ("io_uring: keep table of pointers to ubufs")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
>  fs/io_uring.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index 57a64c7e0e69..f4ec092c23f4 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -8269,7 +8269,7 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, struct iovec *iov,
>  		goto done;
>  
>  	imu = kvmalloc(struct_size(imu, bvec, nr_pages), GFP_KERNEL);
> -	if (!imu->bvec)
> +	if (!imu)
>  		goto done;
>  
>  	ret = 0;
> 

-- 
Pavel Begunkov